Inverted microscopes for biological observation have been conventionally known (see Japanese Patent Application Laid-Open No. 10-282430 and Japanese Patent Application Laid-Open No. 8-43741).
In some case, this type of inverted microscope is typically combined with a laser manipulator for manipulating micro objects in cells and an optical system for high SN fluorescent observation by total internal reflection illumination.
The optical system of the laser manipulator and the optical system of high SN fluorescent observation mentioned above are disposed in such a way as to surround the microscope mounted on a base (e.g. vibration isolation table).
Therefore, there arises a problem that when an extension optical device is to be used in combination with a microscope, a large mount space is required.